block_files.h revision 3f50c38dc070f4bb515c1b64450dae14f316474e 
1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// See net/disk_cache/disk_cache.h for the public interface.
6
7#ifndef NET_DISK_CACHE_BLOCK_FILES_H__
8#define NET_DISK_CACHE_BLOCK_FILES_H__
9#pragma once
10
11#include <vector>
12
13#include "base/file_path.h"
14#include "base/gtest_prod_util.h"
15#include "base/scoped_ptr.h"
16#include "net/disk_cache/addr.h"
17#include "net/disk_cache/mapped_file.h"
18
19namespace base {
20class ThreadChecker;
21}
22
23namespace disk_cache {
24
25// This class handles the set of block-files open by the disk cache.
26class BlockFiles {
27 public:
28  explicit BlockFiles(const FilePath& path);
29  ~BlockFiles();
30
31  // Performs the object initialization. create_files indicates if the backing
32  // files should be created or just open.
33  bool Init(bool create_files);
34
35  // Returns the file that stores a given address.
36  MappedFile* GetFile(Addr address);
37
38  // Creates a new entry on a block file. block_type indicates the size of block
39  // to be used (as defined on cache_addr.h), block_count is the number of
40  // blocks to allocate, and block_address is the address of the new entry.
41  bool CreateBlock(FileType block_type, int block_count, Addr* block_address);
42
43  // Removes an entry from the block files. If deep is true, the storage is zero
44  // filled; otherwise the entry is removed but the data is not altered (must be
45  // already zeroed).
46  void DeleteBlock(Addr address, bool deep);
47
48  // Close all the files and set the internal state to be initializad again. The
49  // cache is being purged.
50  void CloseFiles();
51
52  // Sends UMA stats.
53  void ReportStats();
54
55  // Returns true if the blocks pointed by a given address are currently used.
56  // This method is only intended for debugging.
57  bool IsValid(Addr address);
58
59 private:
60  // Set force to true to overwrite the file if it exists.
61  bool CreateBlockFile(int index, FileType file_type, bool force);
62  bool OpenBlockFile(int index);
63
64  // Attemp to grow this file. Fails if the file cannot be extended anymore.
65  bool GrowBlockFile(MappedFile* file, BlockFileHeader* header);
66
67  // Returns the appropriate file to use for a new block.
68  MappedFile* FileForNewBlock(FileType block_type, int block_count);
69
70  // Returns the next block file on this chain, creating new files if needed.
71  MappedFile* NextFile(const MappedFile* file);
72
73  // Creates an empty block file and returns its index.
74  int CreateNextBlockFile(FileType block_type);
75
76  // Removes a chained block file that is now empty.
77  void RemoveEmptyFile(FileType block_type);
78
79  // Restores the header of a potentially inconsistent file.
80  bool FixBlockFileHeader(MappedFile* file);
81
82  // Retrieves stats for the given file index.
83  void GetFileStats(int index, int* used_count, int* load);
84
85  // Returns the filename for a given file index.
86  FilePath Name(int index);
87
88  bool init_;
89  char* zero_buffer_;  // Buffer to speed-up cleaning deleted entries.
90  FilePath path_;  // Path to the backing folder.
91  std::vector<MappedFile*> block_files_;  // The actual files.
92  scoped_ptr<base::ThreadChecker> thread_checker_;
93
94  FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_ZeroSizeFile);
95  FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_InvalidFile);
96  FRIEND_TEST_ALL_PREFIXES(DiskCacheTest, BlockFiles_Stats);
97
98  DISALLOW_COPY_AND_ASSIGN(BlockFiles);
99};
100
101}  // namespace disk_cache
102
103#endif  // NET_DISK_CACHE_BLOCK_FILES_H__
104